Antenna



G. H. BROWN oct. 26, 1937.

ANTENNA Filed' may 14, 193e Gttorneg lli/50A l? 770A/ `50 The lter network 1 is comprised of capacitors In this arrangement,` the antenna for the lower Patented oct. 26, 1937 2,096,782

UNITED sTATEs PATENT oFFicE ANTENNA George H. Brown, Haddonfield, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application May 14, 1936,` Serial No. l79,635

13 Claims. (Cl. Z50-33) This invention relates to antennas. More with'respect to currents of the lower frequency f' specifically to a single antenna which may be opfr., generated by GL, because the filter L1C1 offers erated at desired fractions of wave lengths at a very low impedance to these currents. The anplurality of frequencies without resorting to tenna for the lower frequency f1. is represented by 5 retuning or switch means within the antenna. the solid line 9 and the current distribution there- I am aware that a single antenna system may in by the dash line II. be used to radiate a plurality of fields, generated For currents of the higher frequency fn, the by apparatus operating at different frequencies, filter network C102 and L1 is parallel resonant. by retuning the antenna system. Numerous ar- The resonant filter is located at an effective disrangements have been proposed for switching tance of one-quarter wave length along the lower l0 reactances by means of which antenna systems antenna section 3, and thereby effectively exmay be resonated to a plurality of frequencies. cludes currents of the higher frequency fn from The present invention has for one objective a the uppervsection I. The current distribution of single antenna which may be operated at different the lower section is represented by the dash line effective lengths without requiring either switch- I3, while the antenna is represented as the solid l5 ing apparatus or retuning. Another object is to line I5. arrange a single antenna of the required height at If the signals from the two generators GH. and

one frequency and to automatically vary the cur- GL are to be used alternately, it is simply necesrent distribution so that the effective height at Sary to switch the antenna to the required genersome other frequency is that which has the ator. If simultaneous operation is desired, a 20 required angle of radiation. A further object is pair of filters represented by numerals II and I9 toadapt a single antenna so that its characterisshould be included in the transmissiOIl line betics offer maximum effectiveness for the radiation tween the generators and the antenna. The or reception of fields of two or more different filter I1 connected between GH and the antenna 5,

frequencies. should be designed to offer low impedance to cur- 25 In the accompanying vdrawing Figure 1 is a Tents 0f frequenyfnand high imPedaHCQIJO Culschematic circuit diagram representing one emrents of frequency L LkeWiSe, lte' I9 iS i11- bodiment of my invention, eluded in the transmission line between G1. and

Figure 2 is a circuit diagram of a modified arthe antenna 5. This filter I9 offers low imrangement of antenna system, pedance to currents of frequency fr. and high im- 30 `Figure 3 is a schematic illustration of a filter pedance to currents of frequency fn. network which may be used in the transmission The method of coupling the generators and lines to the antenna, and antenna systems is shown, described and claimed Figure 4 is an arrangement which may be used in U. S. Patent 2,082,096 which issued June 1, 1937 in connection with one form of antenna. on application, Serial No. 50,500 filed November 35 Figure 5A is a plan View of the shielded inductor 19, 1935 by George H BrOWIl and assigned t0 the M section of the antenna illustrated in Fig. 4. same assignee as this application. The schematic Figure 5B is a side elevational View of the circuit arrangement of suitable filters I'I and I9 shielded inductor of Figure 5A. is shown in Figure 3. These filters, connected in j. In' Figure 1, reference numerals I and 3 reprethe transmission line between the generators and 40 sent two sections of an antenna 5. The lower the antenna, prevent the interactions of the two section 3 is, by way of example, of an effective generators. In the event that alternate translength equal to one-quarter wave of currents 0f mission is used, the lters maybe omitted in favor frequency fn from the generator GH. The comof switching the antenna to the required gener,-

bined sections I, 3 have an effective length equal ator. 45

to one-quarter of a wave length of currents of The modification indicated in Figure 2 iS a frequency fr. from the generator GL. The two schematic illustration of an antenna system which antenna sections are connected by a filter netis operated at two frequencies, fn and fL,-fH inwork 1. dicating the higher frequency and fr. the lower.

C1, C2, and inductor L1. The capacitor C1 and frequency may be of the sectionalized type inductor L1 are series resonant to currents of described and claimed in U. S. Patent 2,068,261 frequency fL. Thus the antenna, comprising secwhich issued January 19, 1937 on applicationSerial tions I, 3 and series resonant of lter L1C1 has an No. 33,281, filed July 26, 1935, by George I-I. Brown 55 effective height equal to one-quarter Wave length and assigned to the same assignee as the present ,5,5

application. The antenna sections are represented by reference numeralsZl 23.v The upper section 2 I by way of example, may be of the order of onehalf of the length of the lower.

The upper and lower antenna sections 2|, 23

. are joined by a filter network 25, which is composed of inductors L3 and L4 and capacitor C3. The inductor L3 .and capacitor C3 are made series resonant to currentsrfn from the generatorGH.

The antenna length is chosen as a half-wave length with current distribution represented by the dash line 21. The inductor L4 is of a value which will give the required current` distribution f tionalizing inductor or capacitor at one frequency, while L4 operatesv as the sectionalizing reactance at the other frequency. Inthis man- Y insulated section. The filter network is used.V

to join the sections as described above.

If a tubular mast 3l is used 'as the antenna, as illustrated in Figure 4, Yan enlargedsection 33 may be used as an inductor. This inductor is of toroidal shape and takes the place of inductor L4 of Figure 2. The seriesA resonant circuitris comprised ofthe inner inductor 35 and capacitor 31, which are respectively equivalent to inductor L3 and capacitor C3. This particular arrangement offers several advantages in that no insulationis required between the Aantenna sections, and the inner elements 35, 31 are shielded Within a suitable housing which'is also the outer inductor 33. In this,. aswell as the previously described arrangements, the antennas are preferably insulated from ground. The transmission lines from the generators maybe coupled to the antenna through conventional coupling means.

It should be understood that my invention is not limited to the use of two. frequencies. By employing suitable filters between several sections of proper length, a pluralityof frequencies may Ybe employed and the several sections successively energized to radiate at the predetermined proper wave length. Likewise, the single antenna may be sectionalized for a plurality of frequencies. By the terms sectionalized or sectionalized antenna I mean an antenna in which the current distribution is vadjusted to vary the angle of radiation in accordanceY with a desired relation between the components of ground Wave andsky wave.

I claim as my invention: t

1. An antenna responsive to currents of different frequencies comprising a plurality of sec- Y tions, and a filter network connected between Vandlow frequency comprising a pair of sections,

and a filter connected between said sectionsL Said One filter being series resonant to the currents of the lower frequency and parallel resonant to currents of the higher frequency.

3. An antenna for radiating a high frequency field and a low frequency field comprising a pair of sections, one of said sections having a length substantially equal to a quarter wave length with respect to one of said frequency, and a filter located between said sections, said lter being series resonant to the lower of said Vfrequencies Vand parallel resonant tothe higher of said frequencies.

4. An antenna for radiating a, high frequency field and a low frequency field comprising a pair lof sections, one of said sections having an effective length substantially equal to a quarter wave length of the iield'of higher frequency, and the sum of said sections having an effective length substantially equal to a quarter wave length of 5. An antenna for radiating a'high frequency field and a low frequency field comprising a pair of sections, the effective length of Vthe sum of said sections being substantially equal to one-half wave length of said high frequency field, and a filter connecting saidv sections offering low impedance to currents of said high frequency, and

offering reactance to currents of said low frequency to thereby adjust the current distribution and angle of radiation of said low frequency field.

6.7An antenna for radiating a high frequency field and a low frequency field comprising a pair of sections, and a filter connecting said sections offering different values of reactance to currents of said frequencies and so constructed and arranged that the distribution of currents of Y said frequencies may be varied to establish-desired angles of radiation of said fields.

7. In a device of the character of claim 6 a pair of generators of currents of said high and low frequencies and means coupling said generators to said antenna.

8. In a device of the character of claim 3 a. generator of currentsv of said high frequency, a generator of Ycurrents of said low frequency, a filter connected between said generators and said antenna offering high impedance to currents tending to fiow between the generators and low impedance to currents flowing from either 'generator to said antenna. 'f

9. In a device of the character of claim 5 a pair of generators of currents of said high and low frequencies and means coupling said generators to said antenna. Y

10. In aV device of the character of claim 5 a generator of currents of said high frequency, a generator of currents of said low frequency, a

filter connected between said generators andV Y pair of generators of currents of said high-and lcw frequencies and means coupling said generators to said antenna. Y

12. In a device of the character of claim 6 a generator of currents of said high frequency, a

generator of currents of said lowV frequency, a filter connected between said generators `and said antenna offering high impedance to currents tending to oW between the generators and 10W impedance to currents owing from either generator to said antenna.

13. In a device of the character of claim 4 a. generator of currents of said high frequency, a generator of currents of said 10W frequency, a

filter connected between said generators and said antenna roffering high impedance to currents tending to oW between the generators yand 10W impedance to currents flowing'from either generator to said antenna.

GEORGE; H. BROWN. 

